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Old 14-08-2013, 10:52   #1
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Using Only One Engine

Is it possible to use only one engine to save fuel. We are buying a trawler in the next year and while I prefer a single engine, a lot of the boats I like have two. Are there drawbacks to shutting down one engine while on a voyage to save fuel? Is there additional strain on the rudder posts because of the yaw induced by using an off center engine?
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Old 14-08-2013, 10:58   #2
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Re: Using only one engine

I see many cats and power boats running on one engine now because of fuel costs.
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Old 15-08-2013, 10:07   #3
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Re: Using only one engine

There have been several discussion about running on one engine. the general consensus is you might be able to save some fuel but not as much as you might think and not worth it as the higher rpm’s required. The biggest is that many boats can/do not run in a straight line so the rudder has to be hard over and/pr constantly having to correct.

Lastly is the question about the non power free turning prop, will the transmission allow for a free turning prop, many do not. Also the free willing prop will great a drag and with the hard over rudders there is very little fuel savings. Bottom line is best and just as cheap to slow down to hull speed.
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Old 15-08-2013, 10:16   #4
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Re: Using only one engine

Yep, transmission lubrication.. and drag. The specific transmission maker can speak to the former. Also, steering is little goofy when hard over to compensate; less range of movement left, at least in one direction or the other.

Also, just because two mains are running, that doesn't necessarily mean twice as much fuel burn in the first place. If 300 horsepower (for example) is required to move a boat at or under it's theoretical hull speed, that can come from one engine.. or from two, each providing about half of that 300 HP. The two smaller engines (or two engines running at lower RPMs) may burn closer to only 1.5x (or even less) than the single engine version.

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Old 15-08-2013, 11:12   #5
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Re: Using Only One Engine

OK, thanks. Now, does anyone have any experience with fuel usage on a Defever 44? Most have 2 120 lehmans that burn about 2 gph @ 9 knts according to the reviews I've read. Anyone have a Defever and know what the actual usage is at 7-8 knts?
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